The invention relates to improvements in methods of and in apparatus for subdividing webs or strips of paper, metallic foil, plastic foil or a combination of such or similar materials. More particularly, the invention relates to improvements in methods of and in apparatus for subdividing webs into sections of predetermined length. Still more particularly, the invention relates to improvements in methods of and in apparatus for subdividing running webs of coherent labels and/or blanks of wrapping material into a series of discrete sections having a predetermined length.
It is already known to subdivide a running web into sections of desired length by resorting to an apparatus wherein a conveyor advances the web along a predetermined path and a severing device employing at least one orbiting knife is utilized to sever the running web in a predetermined portion of its path. The web is drawn off a bobbin or another suitable source of supply. Reference may be had, for example, to German Pat. No. 24 35 441 C which discloses an apparatus wherein an orbiting knife cooperates with a counterknife to sever the running web at desired intervals. The separated sections of the web can constitute discrete blanks of wrapping material, and such blanks are transported to a packing machine. The leader of a second web is maintained in a state of readiness at the severing station in order to avoid prolonged interruptions of delivery of blanks to the packing machine when the preceding web has expired. The second web is set in motion in response to expiration of the preceding web. The last blanks which are separated from the expiring web and/or the foremost blanks which are separated from the next-following web normally exhibit defects, or the last blank which was severed from the expiring web is followed by a gap which, in turn, is followed by the first blank severed from the next-following web. This creates numerous problems in that certain objects which are to be wrapped in the packing machine are not wrapped at all and certain other objects are draped into defective blanks so that the finished products must be monitored and the products exhibiting defective wrappers must be segregated from satisfactorily wrapped products. All this contributes to the cost of the ultimate products and reduces the output of the packing machine.
German Pat. No. 12 33 686 discloses an apparatus which renders it possible to place the trailing end of an expiring web end-to-end with the leader of the next-following web without resorting to an adhesive. However, the operation of such apparatus (as well as the operation of apparatus disclosed in German Pat. No. 24 35 441 C) cannot be interrupted if the proper relationship of successively severed sections relative to each other is to be maintained.
On the other hand, it happens again and again that the operation of an apparatus which is to subdivide running webs of paper or other flexible material into individual sections of desired length must be interrupted for any one of a number of reasons. For example, a web which carries a series of labels can exhibit portions which are devoid of labels or carry defective labels. Furthermore, the operation of the apparatus must be interrupted upon completion of a shift or for the purpose of inspecting the severing apparatus and/or the machine or plant which receives severed sections from the severing apparatus. The interruptions can be very short or they can last for extended periods of time.
Accordingly, there exists an urgent need for methods of and for apparatus for subdividing webs of coherent labels, blanks of wrapping material or the like into sections of predetermined length (e.g., unit length) in such a way that the operation can be interrupted for a desired interval or time and thereupon restarted without the making of unsatisfactory sections and/or without interrupting the delivery of successively severed sections to one or more consuming machines.